The present invention generally relates to translucent personal cleansing bars, and a method for making same. More particularly, the invention relates to a translucent soap bar having enhanced lather and tactile properties.
Soaps made from mixtures of animal fats and vegetable oils have been made for many years. Today, the majority of personal cleansing/soap bars are made from a mixture of tallow and coconut oil or from the fatty acids obtained from such oils. Such products have, for the most part, been accepted by consumers, although improvements in certain of their properties are constantly being sought.
Aside from improvements in the cleaning, lathering and rinsing properties of personal cleansing bars, the aesthetic appearance of these bars has also grown to be increasingly important to consumers. There is a general consensus among today s consumers that a clear, i.e., less opaque personal cleansing bar is more desirable than a conventional opaque bar. The reasons for this may stem from the consumers belief that such bars are somehow more natural or contain fewer undesirable constituents or that a translucent or transparent soap bar contains ingredients that are more easily rinsed from the skin after washing. Regardless of the reasons for this belief, in an effort to appease consumers desires, manufacturers have begun making transparent and translucent personal cleansing bars.
Transparent soap bars depend for their distinctive appearance upon the fact that the soap has an ultramicrocrystalline form. The incorporation of glycerol and sugars also tend to cause soap to assume this form. The effect is entirely physical, and depends upon the conditions under which the soap crystallizes rather than the presence of alcohol or any other substance in the finished soap cake. Thus, a transparent soap made with the aid of alcohol retains its appearance after most of the alcohol has been evaporated from it.
Transparent soaps vary greatly in composition. They may be prepared simply by dissolving soap flakes in alcohol and then driving off the greater part of the alcohol. Such a product will not be greatly different in composition from the original soap flakes. A more usual method of manufacture, however, is to add alcohol and glycerol, in the proportion of about two parts of alcohol to one of glycerol, to a hot saponified batch of semi-boiled soap until a rapidly cooled sample is clear, after which the batch is framed in the usual way. Sugar may also be added. The fats used in transparent soaps usually are tallow and coconut oil. Up to about 30% castor oil is often used in the fat charge, as the presence of this oil reduces the amount of alcohol, glycerol or sugar required to render the soap transparent. The anhydrous soap content of transparent soaps is usually well under 50%. A soap bar is deemed to be transparent when 12 pt type is readable through a one inch thick bar.
Soap translucency is quantified using the contrast ratio method for measuring opacity. The opacity value gives an inverse measurement of translucency. According to this method, a 5/8 inch (16 mm) thick personal cleansing bar, which is flat on two parallel faces, is first formed. A Pacific Scientific Colorgard System/05 Colorimeter, similar to a Hunter Tristimulus Colorimeter) is then calibrated and used to obtain two measurements. The first measurement is taken with the translucent bar backed by a white tile, placed over a light source, to achieve maximum reflectance of the light which passes through the sample. The second measurement is then taken with the translucent bar backed by a black tile, placed over a light source, for minimum reflectance of light through the sample. The percent opacity is then defined as the value of the second measurement divided by the first measurement multiplied by one hundred.
Thus, a transparent soap bar has a percent opacity for a 5/8 inch to 3/4 inch thick bar of less than 40 percent. A typical value of 20 to 35 percent opacity is often achieved.
Translucent bars, on the other hand, are not as clear as transparent bars, i.e., they possess a higher degree of opacity than that of a transparent bar. A bar is deemed to be translucent when its percent opacity is from 40 to 85%. Similarly, a bar is deemed to be opaque when its percent opacity is greater than 85%.